Blown Inverter Fuse?

[TravisH]

Hi,

On the road and foolishly tried to run my 17 amp coffee maker from an inverter outlet. Tripped the breaker on the inverter (the main 15 amp break on the panel did not trip). The breaker on the inverter will not reset. The toggle feelf frozen, locked in place.

It's a WFCO WF-5220R True Sine Wave in a 2019 FC. It's the stock inverter.

I gather it's a non-resettable class T fuse but have not been able to locate it yet. Is this a common fuse? I find none on like Amazon and there is no RV/Airstream dealer nearby. Manual says a 100 amp fuse!!! I can't imagine blowing a 100amp fuse with a 17 amp coffee maker.....

Thanks!

Trav

[Piggy Bank]

This is the fuse our inverter uses. We have a 2019 FC 27 foot.
https://www.amazon.com/gp/product/B0...e?ie=UTF8&th=1

[Piggy Bank]

We have blown ours when reinstalling our batteries in the spring (we run on a trickle charger at home during the winter). Found out about this fuse the first time we blew it when boondocing once in Yellowstone. A very kind fellow air streamer there had a spare which he sold to us at cost. Now we carry a spare.

[TravisH]

Originally Posted by Piggy Bank

This is the fuse our inverter uses. We have a 2019 FC 27 foot.
https://www.amazon.com/gp/product/B0...e?ie=UTF8&th=1

YES!

Mine is almost like that but part #28418!

I saw one thread that had me looking inside under the bed near the inveter before I traced the wires back to the battery!

[SSquared]

Originally Posted by TravisH

I gather it's a non-resettable class T fuse but have not been able to locate it yet. Is this a common fuse? I find none on like Amazon and there is no RV/Airstream dealer nearby. Manual says a 100 amp fuse!!! I can't imagine blowing a 100amp fuse with a 17 amp coffee maker.....

Thanks!

Trav

My trailer did not come with an inverter, and I don't have that kind of fuse.
But I want to share some electrical math with you. The inverter outlets are 120 volts. Your coffee maker is a 120 volt appliance that draws 17 amps of 120 volts. You multiply those together to get watts: 2040 watts. Your inverter has to supply 2040 watts. It gets that from your 12 volt batteries. To see how many amps, divide 2040 by 12: 170 amps from the batteries. (plus there will be some losses, so probably about 190 amps). So yes, you can blow a 100 amp fuse easily.

Oh, and your inverter is rated for 2000 "VA". VA is sort of like watts (it's complicated). The inverter specifications do allow you to briefly exceed the rating, including up to 20% over for no more than one minute.

[sb55]

I have plugged in a space heater into the inverter outlet for years with no problem. The last trip this changed and something tripped. No inverter outlets in the trailer worked at all. It wasn't the actual circuit breaker in the panel, but it tripped the circuit breaker on the actual inverter. Once I figured this out and reset it, all was fine. Now the space heater is plugged into a different outlet. Of course, now it has to be turned off when the coffee maker is brewing, or that 15 amp GFCI breaker will trip!

[JeffKim]

That's a lot of amps for a cofee maker. Most are in the 1200W range at the most, so about 10A. Are you sure? Since it didn't trip the breaker, I'm wondering if there is something fishy with the inverter.

[TravisH]

Originally Posted by SSquared

My trailer did not come with an inverter, and I don't have that kind of fuse.
But I want to share some electrical math with you. The inverter outlets are 120 volts. Your coffee maker is a 120 volt appliance that draws 17 amps of 120 volts. You multiply those together to get watts: 2040 watts. Your inverter has to supply 2040 watts. It gets that from your 12 volt batteries. To see how many amps, divide 2040 by 12: 170 amps from the batteries. (plus there will be some losses, so probably about 190 amps). So yes, you can blow a 100 amp fuse easily.

Oh, and your inverter is rated for 2000 "VA". VA is sort of like watts (it's complicated). The inverter specifications do allow you to briefly exceed the rating, including up to 20% over for no more than one minute.

^^^^^^^^^^^^^^^^THIS^^^^^^^^^^^^^^^^

If anyone in the future is reading this THIS thread is what you MUST understand!

Basically you HAVE to understand wattage and not look at simply amps which is WHY appliances usually are rated in watts. Watts=volts x amps. So as SSquared explained it's very easy to overload the inverter circuit!

Get a bigger one or just use for TV etc AFTER you confirm watts fall within the parameters SSquared explained.


BTW the fuse was IMPOSSIBLE to find! I hit 4 or 5 RV supply stores, even an Airstream dealer and 3 or 4 hardware stores! Amazon had it for ~$20

[uncle_bob]

Hi

I've found the typical class T fuse at Lowes and also at Home Depot. It's not a stock item everywhere so you may or may not find it. When I did it was around $80 vs the Amazon < $30 price.

Bob

[DaveG]

Originally Posted by JeffKim

That's a lot of amps for a cofee maker. Most are in the 1200W range at the most, so about 10A. Are you sure? Since it didn't trip the breaker, I'm wondering if there is something fishy with the inverter.

Agree with 1200 watt range as common (10 to 12 amps) with most coffee makers.
Not familiar with this fuse but a fuse link will degrade over time like a filament in a light bulb. With regular use over five years it may have just failed from age.

[JeffKim]

Originally Posted by DaveG

Agree with 1200 watt range as common (10 to 12 amps) with most coffee makers.
Not familiar with this fuse but a fuse link will degrade over time like a filament in a light bulb. With regular use over five years it may have just failed from age.

Well, come to think of it most household circuits are 15A, so I'm pretty sure 17A isn't correct.

[Keys Dave]

To anyone still interested, I am not sure but that fuse looks like one from West Marine. Blue Seas brand. If that store is handy.

[DaveG]

Originally Posted by JeffKim

That's a lot of amps for a cofee maker. Most are in the 1200W range at the most, so about 10A. Are you sure? Since it didn't trip the breaker, I'm wondering if there is something fishy with the inverter.

- And maybe the pot has an issue? Maybe use it on a different power source to see if it trips a circuit.
- The pot should have a label showing power needs.
- Amperage rating doesn't always determine what overcurrent device may trip first. A fuse is usually faster than a breaker at opening a shorted circuit.
- Kind of interested in this thread. Please post how it resolves. Thanks!

[TravisH]

Originally Posted by DaveG

Agree with 1200 watt range as common (10 to 12 amps) with most coffee makers.
Not familiar with this fuse but a fuse link will degrade over time like a filament in a light bulb. With regular use over five years it may have just failed from age.

Originally Posted by DaveG

- And maybe the pot has an issue? Maybe use it on a different power source to see if it trips a circuit.
- The pot should have a label showing power needs.
- Amperage rating doesn't always determine what overcurrent device may trip first. A fuse is usually faster than a breaker at opening a shorted circuit.
- Kind of interested in this thread. Please post how it resolves. Thanks!

See above. 1200 watts is 12 amps at 110v BUT at 12v it's 100 amps!

Watts are what matter! We don't think watts when on shore power but you have to start to equation with 12 volts! so in my case 1700 watts was pulling 141 amps! YIKES

[TravisH]

Originally Posted by Keys Dave

To anyone still interested, I am not sure but that fuse looks like one from West Marine. Blue Seas brand. If that store is handy.

Originally Posted by uncle_bob

Hi

I've found the typical class T fuse at Lowes and also at Home Depot. It's not a stock item everywhere so you may or may not find it. When I did it was around $80 vs the Amazon < $30 price.

Bob

I could not find on the shelf anywhere. Even West Marine in San Diego had none. Found it on Amazon. Actually got two for $18! That's not mentioned in the listing but came in a two pack and no others offered in that wattage.

Here's the link for future searches:

https://www.amazon.com/Bussman-TERMA...d_i=B08LZS88W8

[Wazbro]

Originally Posted by TravisH

See above. 1200 watts is 12 amps at 110v BUT at 12v it's 100 amps!

Watts are what matter! We don't think watts when on shore power but you have to start to equation with 12 volts! so in my case 1700 watts was pulling 141 amps! YIKES

Well 1200 watts is 10 amps at 120 volts, 11 amps at 110 volts and 12 amps at 100 volts.

That 141 amps at 12 volts is at 100% efficiency, which I know you're not getting, you would be lucky to be under 160 amps.

[uncle_bob]

Hi

As long as we're going a bit crazy on numbers ....

A 10A fuse (or breaker) will *pass* 10A. It should be happy pretty much forever if you just run 10A through it. It won't blow or trip.

Yes, like everything else on the planet, they do wear out eventually. All your "electrical stuff" will wear out quicker as you go past 80% of the current rating. (The heat involved doubles when you go from 70% to 100% ....).

A 10A breaker may well take many seconds to trip if you put 20A through it. If you are looking for a whole lot of fun, you can dig into the spec's on your breakers and see just how many minutes / seconds they are supposed to pass this or that excess current.

Fuses come in a wide range of types. Some trip pretty quick. Some trip pretty slowly. Get them hot and they trip at a lower current than they do cold.

Like a lot of things, you can indeed get crummy fuses. They may trip fast, they may trip slow. Indeed there are a number of fun stories involving smoke pouring out of this or that building involving big expensive breakers that didn't do what they should have ....

Fuses and breakers are there as a last resort protection for the wires. Don't trust them to measure current

Bob